This invention relates to providing a high resolution side-looking airborne radar antenna by a modification in an airworthy fashion of the straight planiform fuselage of a modern airliner, together with the wing to produce a high gain, very low-side lobe fixed beam from a ray-fed lens structure which is essentially frequency insensitive. More particularly, the lens structure includes a half-lens in double-traversal over a flat metal reflector, or a similar double-traversal lens in a metal parabolic dish to trim the aerodynamic cross section.
Modern high resolution radar dictates the requirement for large antenna apertures to generate narrow microwave beams. The apertures typically required for such a radar are between 6 to 10 feet in diameter. For airborne applications, an aperture of this size generates both technical as well as cost problems. When a seven-foot diameter parabolic dish was mated with the nose cone of a jet aircraft, it was found necessary to carry out extensive structural modifications at high cost and the resulting configuration of the aircraft produced excessive drag.
When the mission permits the use of a side-looking radar, such as a severe weather probe and hurricane mapping, a much less expensive and highly effective antenna is desirable as an alternative to a conventional nose cone mounted parabolic dish antenna. Microwave lenses are per se known in the art as shown, for example, in U.S. Pat. No. 2,705,753.